Allow the driver to do specific remapping of column types for cases
where not all types are supported.

Allow the driver to do specific remapping of column types for cases
where not all types are supported. Classes that want to do custom type
mapping for columns should override the customColumnTypeMap method.

This indicates that Schemifier needs to run with a non-transacted
connection.

This indicates that Schemifier needs to run with a non-transacted
connection. Certain databases require that gathering information
on tables (which Schemifier uses for updates) run outside of a transaction.